1. Field of the Invention
This invention relates to a speed change gear shift rod.
2. Description of the Prior Art
Conventional speed change gear shift rods usually take the form of the unit illustrated in FIG. 1. That is, a shaft end section 105a of shift rod 105 is supported so that it is freely slideable in the direction of the shaft in a blind supporting hole 103 provided in a main casing 101. A slotted oil channel 107 is formed by the shaft end section 105a in the supporting hole 103, to divert oil from the inside to the outside of the supporting hole 103 when said shaft end section 105a slides toward the back of the supporting hole 103 as a result of the speed change action. Furthermore, a shift fork, which is not illustrated in the figure, is fixed on the shift rod 105, and this shift fork is connected both to a sleeve and to an action lever, neither of which is shown in the figure. Accordingly, when the shift fork is moved by means of the action lever, the sleeve is made to move by means of the shift rod, and the speed change of the speed shift gear is carried out. At that time, both the shift fork and the shift rod 105 move in the direction of the shaft, and an end surface 105b of the shaft end section 105a touches a back surface 103a of the supporting hole 103, and determines the position of the shift rod 105 and the shift fork. In addition, the lubricating oil which is thrown upward from the rotation of the gear and the like, enters the supporting hole 103, but this lubricating oil is expelled from an oil channel 107 when the shaft end section 105a slides to the back side of the supporting hole 103, and the sliding action of the shift rod 105 is not impeded.
However, with this type of conventional construction, the end surface 105b of the shift rod 105 impacts against the back surface 103a of the supporting hole 103 bacause of the speed changing action, and, as a result of this impacting, a percussive opposing force acts against the shift lever and becomes a hindrance to the operating feel of the shift lever. In addition, after the operation, the end surface 105b remains touching the back surface 103a of the supporting hole 103, and, because of this, an allophone is developed at the gap between the end surface 105b and the back surface 103a because of vibration, and this vibration is input directly from the back surface 103a of the supporting hole 103 in the shaft direction along the shaft end section 105a, causing the fear that a gear disengagement could occur.
To counteract this, a suitable flange section or difference in level is provided on top of the shift rod 105 in the neighborhood of the mouth of the supporting hole 103, and an elastic body is used as to link the space between this flange section or difference in level and the circumference of the rim of the mouth of the supporting hole 103, intended to act as a cushion during operation. However, in this case, even the provision of a flange section and the like on the shift rod 105 causes problems such as increase in weight and complication of the construction.